From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37598) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ao7jX-0005Pn-Bp for qemu-devel@nongnu.org; Thu, 07 Apr 2016 07:04:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ao7jU-0007cK-VV for qemu-devel@nongnu.org; Thu, 07 Apr 2016 07:04:19 -0400 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:34031) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ao7jU-0007c8-PU for qemu-devel@nongnu.org; Thu, 07 Apr 2016 07:04:16 -0400 From: Samuel Thibault Date: Thu, 7 Apr 2016 13:04:11 +0200 Message-Id: <1460027053-21211-3-git-send-email-samuel.thibault@ens-lyon.org> In-Reply-To: <1460027053-21211-1-git-send-email-samuel.thibault@ens-lyon.org> References: <1460027053-21211-1-git-send-email-samuel.thibault@ens-lyon.org> Subject: [Qemu-devel] [PULL 2/4] slirp: avoid use-after-free in slirp_pollfds_poll() if soread() returns an error List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, peter.maydell@linaro.org Cc: steven@steven676.net, jan.kiszka@siemens.com, Steven Luo , Samuel Thibault , edgar.iglesias@gmail.com From: Steven Luo Samuel Thibault pointed out that it's possible that slirp_pollfds_poll() will try to use a socket even after soread() returns an error, resulting in an use-after-free if the socket was removed while handling the error. Avoid this by refusing to continue to work with the socket in this case. Signed-off-by: Steven Luo Signed-off-by: Samuel Thibault --- slirp/slirp.c | 12 +++++++++++- slirp/socket.c | 17 +++++++++++------ slirp/socket.h | 2 +- 3 files changed, 23 insertions(+), 8 deletions(-) diff --git a/slirp/slirp.c b/slirp/slirp.c index fef526c..9f4bea3 100644 --- a/slirp/slirp.c +++ b/slirp/slirp.c @@ -534,7 +534,12 @@ void slirp_pollfds_poll(GArray *pollfds, int select_error) * test for G_IO_IN below if this succeeds */ if (revents & G_IO_PRI) { - sorecvoob(so); + ret = sorecvoob(so); + if (ret < 0) { + /* Socket error might have resulted in the socket being + * removed, do not try to do anything more with it. */ + continue; + } } /* * Check sockets for reading @@ -553,6 +558,11 @@ void slirp_pollfds_poll(GArray *pollfds, int select_error) if (ret > 0) { tcp_output(sototcpcb(so)); } + if (ret < 0) { + /* Socket error might have resulted in the socket being + * removed, do not try to do anything more with it. */ + continue; + } } /* diff --git a/slirp/socket.c b/slirp/socket.c index b836c42..7f022a6 100644 --- a/slirp/socket.c +++ b/slirp/socket.c @@ -260,10 +260,11 @@ err: * so when OOB data arrives, we soread() it and everything * in the send buffer is sent as urgent data */ -void +int sorecvoob(struct socket *so) { struct tcpcb *tp = sototcpcb(so); + int ret; DEBUG_CALL("sorecvoob"); DEBUG_ARG("so = %p", so); @@ -276,11 +277,15 @@ sorecvoob(struct socket *so) * urgent data, or the read() doesn't return all the * urgent data. */ - soread(so); - tp->snd_up = tp->snd_una + so->so_snd.sb_cc; - tp->t_force = 1; - tcp_output(tp); - tp->t_force = 0; + ret = soread(so); + if (ret > 0) { + tp->snd_up = tp->snd_una + so->so_snd.sb_cc; + tp->t_force = 1; + tcp_output(tp); + tp->t_force = 0; + } + + return ret; } /* diff --git a/slirp/socket.h b/slirp/socket.h index e9c9b05..7dca506 100644 --- a/slirp/socket.h +++ b/slirp/socket.h @@ -127,7 +127,7 @@ struct socket *solookup(struct socket **, struct socket *, struct socket *socreate(Slirp *); void sofree(struct socket *); int soread(struct socket *); -void sorecvoob(struct socket *); +int sorecvoob(struct socket *); int sosendoob(struct socket *); int sowrite(struct socket *); void sorecvfrom(struct socket *); -- 2.8.0.rc3